What is the IMA of a pulley?

The statement that a pulley has an ideal mechanical advantage (IMA) of 1 because it changes the direction of the force is accurate for a simple pulley system. In this context, the IMA is defined as the ratio of the output force exerted by the machine to the input force applied to it.

For a single fixed pulley, it does not increase the amount of work done or the output force; instead, it merely allows the user to pull down on the rope to lift an object upwards. This direction change simplifies lifting tasks but does not provide a mechanical advantage in terms of the magnitude of the force. Thus, the IMA is 1, indicating that the entire force applied is still required to lift the load vertically, albeit with a change in direction.

Other choices imply varying levels of mechanical advantage without considering the fundamental characteristics and functions of a simple pulley system. While other types of pulleys can provide different IMAs depending on how they are configured (for example, block and tackle systems), the basic single fixed pulley defines the IMA as 1 due to its direct relationship between input and output forces without amplification.